1. Field of the Invention
The present invention relates to a color picture tube device that deflects a plurality of electron beams which are emitted from an electron gun having a plurality of in-line cathodes, and displays a color image on a phosphor screen.
2. Related Art
In a color picture tube device having an in-line electron gun in which cathodes corresponding to the three colors of red (R), green (G), and blue (B) are horizontally aligned, three electron beams emitted from the electron gun need to come together at an appropriate position on a phosphor screen (this is called “convergence”). Self convergence and dynamic convergence are conventional techniques which are widely used for producing convergence. Also, various techniques have been proposed for correcting different kinds of misconvergence.
One method of correcting misconvergence is a dynamic convergence technique synchronous with horizontal deflection, which rectifies a horizontal deflection current and supplies it to a quadrupole coil provided on the electron gun side of a deflection yoke (e.g. Proceedings of the SID, vol. 31/3, 1990, p. 205, DEFLECTION YOKE FOR SUPER-FINE-PITCH 20-in. (19V) IN-LINE COLOR CRT (TRINITRON)). However, due to the need for rectifying a horizontal deflection current of high frequency, such a horizontal deflection-synchronizing dynamic convergence technique has the drawbacks of increases in manufacturing cost and in power consumption.